Boston investigation finds female DNA on pressure cooker bomb

Lab work has turned up a surprising new clue in the Boston Marathon bombings case.

Investigators have found female DNA on one of the pressure cooker bombs.

Sources say it is unclear whether the DNA is from a victim in the attack or from someone who handled components of the bomb before it was put together.

That could be someone in a store or factory, or a co-conspirator.

The FBI has searched the family home of Tamerlan Tsarnaev's widow, Katherine Russell, and they've obtained a sample of her DNA.

His widow plans to ask the Massachusetts medical examiner to release his body to his family, her attorney said Tuesday.

Attorney Amato DeLuca said in a statement that Katherine Russell wants Tamerlan Tsarnaev's remains released to the Tsarnaev family.

Tsarnaev, 26, died after a gunfight with authorities. Police said he ran out of ammunition before his brother, 19-year-old Dzhokhar Tsarnaev, dragged his body under a vehicle while fleeing the scene.

Authorities say the medical examiner has determined the cause of Tamerlan Tsarnaev's death but it will remain private until his remains are released and a death certificate is filed. His parents are still in Russia, but he has relatives in the U.S.

Dzhokhar Tsarnaev is charged with using a weapon of mass destruction to kill, a crime that carries a potential death sentence. He lies in a prison hospital after being wounded in the shootout with police as he and his brother made their getaway attempt.

DeLuca said Tamerlan Tsarnaev's widow met with law enforcement "for many hours over the past week" and will continue cooperating. FBI agents on Monday visited her parents' North Kingstown, R.I., home, where she has been staying, and carried away several bags.

"Katherine and her family continue to be deeply saddened by the harm that has been caused," DeLuca said Tuesday.

Terrel Harris, a spokesman for the Department of Public Safety, said Tuesday evening that the state had not yet received Russell's request to release her husband's body.

He said arrangements must be made to release the body and once that happens a death certificate will be filed and the cause of death made public. He said it is too soon to speculate on when that might happen.

Meanwhile, the last remaining marathon bombing patient has improved from critical to severe. The patient is being treated at Boston Medical Center.

The surviving suspect, Dzokhar Tsarnaev, is getting some high-profile help. Judy Clarke, a prominent death penalty lawyer whose past clients are a notorious who's who that includes Unabomber Ted Kaczynski, Susan Smith (the Texas mom who drowned her two children) and most recently, Tucson shooter Jared Loughner, is joining the defense team.

US Magistrate Judge Marianne Bowler rejected the request for a second death penalty expert. Clark successfully saved Kaczynski, Smith and Loughner from receiving a death sentence.

Tsarnaev has been charged with using a weapon of mass destruction during the April 15 marathon. Three people were killed and more than 260 injured when two bombs exploded near the finish line.